In recent years, it has been found that chalcogenide glasses such as arsenic trisulfide, selenium-germanium glasses and the like are useful for producing resists and for related purposes. These glasses can be placed on suitable substrates in very thin layers and, being amorphous, they have very uniform physical characteristics. They can be readily etched into resist designs: after exposure to a light image or other activating radiation image the chalcogenide glass itself has an image which is differentially resistant to an alkaline etch.
More recently, it has been found that an image of silver on a chalcogenide glass layer can be diffused into or driven into the surface of the glass by light, heat, or preferably, infra red or similar radiation. The silver image has been produced by depositing a silver halide on the glass, exposing it photographically to a pattern to be reproduced and developing it, thus converting some of the silver halide to silver. The silver halide does not respond to infra red radiation while the reduced silver is driven into the surface of the chalcogenide glass thus forming an image configuration of a hard or etch resistant cap on the glass. In our prior application Ser. No. 86,198 , which is a continuation-in-part of Ser. No. 57,183, filed July 13, 1979, a silver halide deposit on the chalcogenide glass surface is exposed to activating radiation and is photographically developed and processed to produce a silver image on the glass. This image is then used to provide an etch resistant cap at the glass surface. The silver required for cap formation can be generated by a relatively short exposure to a light image, or by a relatively short exposure to other activating radiation such as electron beam writing or the like, followed by development.
Resists formed in this way are useful for various micro-resist purposes, including microlithographic purposes; one particularly valuable consequence is the ability to form particularly fine-resolution masks for semiconductor production.